ATF CLAMP-ON FROST PROTECTION THERMOSTAT The ATF clamp-on pipe thermostat has a set range of 10-90°C. The lower set point of 0°C makes the thermostat particularly suited for frost protection applications. The ATF which utilises a vapour filled bellows, comes with pipe fixing strap. The ATF can be used in most frost protection applications which require a pipe thermostat including: 2nd stage operation in 2 stage frost protection schemes and frost protection termination function in systems which utilise a room thermostat to initiate boiler operation during periods of low internal room temperature.